There isn't much, as non-celiac gluten sensitivity is just beginning to be recognized as a real phenomenon by scholars in the field. I doubt it will be very long though. This study states:

Patients with [gluten sensitivity] do not present significant autoimmune or allergic comorbidities, and, as we also have shown here, the serology for common autoantibodies, including anti-tTG IgA, is negative.

There is a need for more research here as the anecdotal evidence (like Dr. Wahl's recovery) seems to point to a link.

A 2010 paper in gut microbes showed a decrease in inflammation in non-celiac patients in response to a gluten free diet. It's unclear what caused this reduction: the authors posit this was caused be a reduction in bacterial load, but it would need a follow-up study to test that idea. Another possibility could be that the lack of gluten is what reduced the inflammation.

From the paper:

Cytokine production by peripheral
blood mononuclear cells (PBMCs)
stimulated with fecal samples of
healthy individuals before and after
the GFD was also evaluated to
establish the possible relationships
between the stimulus of the gut
microbiota and the host immune
function under this dietary
practice.11 PBMC cultures were
considered a good in vitro model for
such studies since monocytes of the
intestinal mucosa are known to be
constantly replenished by blood
monocytes.14 Immunostimulatory
properties of feces, which up to 50%
can be represented by bacteria, were
remarkably reduced as a consequence of
the GFD, inducing a significantly
lower production of pro-inflammatory
cytokines and chemokines (TNF??, IFN??
and IL-8) and anti-inflammatory
cytokines (IL-10) in PBMCs than those
collected before the GFD. It seems
that GFD led to a generalized
reduction of bacterial-induced
cytokine production as a result of the
generalized reduction of the total
large intestinal bacterial load, as
detected in patients under a
gluten-free diet.8 The fact that the
GFD led to reductions in total
Bifidobacterium and B. longum numbers
could also explain the reductions in
the ability of fecal samples to
stimulate IL-10 production, since
strains of this genus and species
might preferentially stimulate IL-10
secretion.15,16

The Paleo Diet by Cordain mentions Sjogren's in the list of diseases reported to improve. I haven't seen it on the forums. I asked about it on the Neuromyotonia forums and a few said they tried but without success. My suspicion is that many of these will be helped but not cured by diet. As frequently discussed here, adrenal exhaustion (aka HPA axis dysfunctionis probably also a big contributor, though sadly there is little to any research to that effect right now. Hormones control Homeostatis and are the difference between a tolerant immune system and one that goes bonkers. It's also not clear if these lifestyle changes only prevent disease or can also cure them, as once the process has started it may feed upon itself.